Screening Cold Tolerance in St. Augustinegrass (Stenotaphrum secundatum (Walt.) Kuntze) for USDA Hardiness Zone 7

Abstract

Among warm-season turfgrasses, St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] generally has poor cold tolerance yet excellent shade tolerance. As mostly hot summers follow cold winters in USDA Hardiness Zone 7, severely damaging tall fescue [Festuca arundineacea Schreb.] and centipedegrass [Eremochloa ophiuroides (Munro) Hack.], a St. Augustinegrass cultivar cold tolerant enough to be grown for shady lawns would greatly benefit both home owners and sod growers in this and potentially other regions. Eight St. Augustinegrass samples were selected from an initial collection of 30, including industry standards ‘Raleigh’ and ‘Palmetto’, for further testing from an established germplasm collection of material collected from lawns grown in USDA Hardiness Zone 7. Percent regrowth was calculated 4 weeks after samples underwent a 2 week cold acclimation process, followed by freezing at 0°C, -4°C, and -6°C separately for 3 h. The germplasm samples designated at ‘A’, ‘G’, and ‘H’ had greater clipping regrowth percentages compared to the industry cold tolerant standard, ‘Raleigh’ at either -4°C and -6°C indicating possible increased cold tolerance for several selections compared to ‘Raleigh’. An increased cold tolerant St. Augustinegrass would provide a wider selection of desirable turfgrasses in the transition zone growing region of the world, especially shady sites.